1. Field of the Invention
This invention relates to a process for polymerizing polar acrylic or maleimide monomers and to "living" polymers produced by such a process.
2. Background
U.S. Pat. Nos. 4,414,372; 4,417,034; 4,508,880; 4,524,196; 4,581,428; 4,588,795; 4,605,716; 4,622,372; 4,656,233; and 4,681,918, and commonly assigned U.S. patent application Ser. Nos. 660,588 filed Oct. 18, 1984 now U.S. Pat. No. 4,711,942; 912,117 and 912,118 filed Sept. 29, 1986 now U.S. Pat. No. 4,732,955; 934,826 filed Nov. 25, 1986 now U.S. Pat. No. 4,783,500; 004,831 filed Jan. 13, 1987 now U.S. Pat. No. 4,822,859; 007,758 filed Jan. 27, 1987 now U.S. Pat. No. 4,806,605; 015,727 filed Feb. 27, 1987 now U.S. Pat. No. 4,736,003; and 048,958 filed May 19, 1987 now abandoned, referred to hereinafter as "the aforesaid patents and patent applications", disclose processes for polymerizing a polar acrylic or maleimide monomer to a "living" polymer in the presence of an initiator, which is a tetracoordinate organosilicon, organotin or organogermanium compound having at least one initiating site, and a co-catalyst which is a source of fluoride, cyanide or azide ions or a suitable Lewis acid, Lewis base or selected oxyanion. Such polymerization processes have become known in the art as Group Transfer Polymerization (Webster et al., J. Amer. Chem. Soc., 105, 5706 (1983)). The aforesaid patents and patent applications disclose that preferred monomers for use in Group Transfer Polymerization are selected from acrylic and maleimide monomers of the formula CH.sub.2 .dbd.C(Y)X and ##STR1## wherein: X is --CN, --CH.dbd.CHC(O)X' or --C(O)X';
Y is --H, --CH.sub.3, --CN or --CO.sub.2 R, provided, however, when X is --CH.dbd.CHC(O)X', Y is --H or --CH.sub.3 ; PA1 X' is --OSi(R.sup.1).sub.3, --R, --OR or --NR'R"; PA1 each R.sup.1, independently, is a hydrocarbyl radical which is an aliphatic, alicyclic, aromatic or mixed aliphatic-aromatic radical containing up to 20 carbon atoms or --H, provided that at least one R.sup.1 group is not --H; PA1 (a) a hydrocarbyl radical which is an aliphatic, alicyclic, aromatic or mixed aliphatic-aromatic radical containing up to 20 carbon atoms; PA1 (b) a polymeric radical containing at least 20 carbon atoms; PA1 (c) a radical of (a) or (b) containing one or more ether oxygen atoms within aliphatic segments thereof; PA1 (d) a radical of (a), (b) or (c) containing one or more functional substituents that are unreactive under polymerizing conditions; and PA1 (e) a radical of (a), (b), (c) or (d) containing one or more reactive substituents of the formula --Z'(O)C--C(Y.sup.1).dbd.CH.sub.2 wherein Y.sup.1 is --H or --CH.sub.3 and Z' is O or NR'; and PA1 (a) a hydrocarbyl radical which is an aliphatic, alicyclic, aromatic or mixed aliphatic-aromatic radical containing up to 20 carbon atoms; PA1 (b) a polymeric radical containing at least 20 carbon atoms; PA1 (c) a radical of (a) or (b) containing one or more ether oxygen atoms within aliphatic segments thereof; PA1 (d) a radical of (a), (b) or (c) containing one or more functional substituents that are unreactive under polymerizing conditions; or PA1 (e) a radical of (a), (b), (c) or (d) containing one or more initiating sites; PA1 (a) a C.sub.1-12 alkyl, C.sub.4-12 cycloalkyl, C.sub.6-12 aralkyl or di(C.sub.1-4 alkyl)amino group; PA1 (b) a group of (a) wherein two or three of the alkyl, cycloalkyl and/or aralkyl groups are joined together by means of one or more carbon-carbon bonds; PA1 (c) a group of (a) or (b) wherein the alkyl, cycloalkyl and/or aralkyl groups contain within aliphatic segments thereof one or more hetero atoms selected from O, N and S; or PA1 (d) a group of (a), (b) or (c) wherein the alkyl, cycloalkyl and/or aralkyl groups contain one or more substituents that are unreactive under polymerizing conditions; and PA1 (a) a hydrocarbyl radical which is an aliphatic, alicyclic, aromatic or mixed aliphatic-aromatic radical containing up to 20 carbon atoms; PA1 (b) a polymeric radical containing at least 20 carbon atoms; PA1 (c) a radical of (a) or (b) containing one or more ether oxygen atoms within aliphatic segments thereof; PA1 (d) a radical of (a), (b) or (c) containing one or more functional substituents that are unreactive under polymerizing conditions; or PA1 (e) a radical of (a), (b), (c) or (d) containing one or more initiating sites;
R is:
each of R' and R" is independently selected from C.sub.1-4 alkyl.
Preferred initiators are selected from tetracoordinate organsilicon, organotin and organogermanium compounds of the formulas (Q').sub.3 MZ, (Q').sub.2 M(Z.sup.1).sub.2, and [Z.sup.1 (Q').sub.2 M].sub.2 O wherein:
each Q', independently, is selected from R.sup.1, OR.sup.1, SR.sup.1 and N(R.sup.1).sub.2 ;
R.sup.1 is as defined above for the monomer;
Z is an activating substituent selected from the group consisting of ##STR2## --OP[OSi(R.sup.1).sub.3 ].sub.2 and mixtures thereof;
R', R", and R are as defined above for the monomer;
X.sup.2 is --OSi(R.sup.1).sub.3, --R.sup.6, --OR.sup.6 or --NR'R";
R.sup.6 is
each of R.sup.2 and R.sup.3 is independently selected from --H and hydrocarbyl, defined as for R.sup.6 above, subparagraphs (a) to (e);
each of R' and R" is independently selected from C.sub.1-4 alkyl;
Z' is as defined above for the monomer;
m is 2, 3 or 4;
n is 3, 4 or 5;
Z.sup.2 is ##STR3## wherein X.sup.2, R.sup.2 and R.sup.3 are as defined above;
at least one of any R, R.sup.2 and R.sup.3 in the initiator contains one or more initiating substituents of the formula --Z.sup.2 --M(R.sup.1).sub.3 wherein R.sup.1 is as defined above and M is as defined below;
Z.sup.2 is a diradical selected from the group ##STR4## thereof, wherein R.sup.2, R.sup.3, X.sup.2, Z', m and n are as defined above;
R.sup.2 and R.sup.3 taken together are ##STR5## provided, however, Z is ##STR6## and/or
X.sup.2 and either R.sup.2 or R.sup.3 taken together are ##STR7##
M is Si, Sn, or Ge, provided, however, when Z is ##STR8##
M is Sn or Ge, and provided, however, when Z.sup.2 is ##STR9## M is Sn or Ge.
In the aforesaid patents and patent applications, preferred co-catalysts are selected from a source of bifluoride ions HF.sub.2.sup.-, or a source of fluoride, cyanide or azide ions, or a source of oxyanions, said oxyanions being capable of forming a conjugate acid having a pKa (DMSO) of about 5 to about 24, preferably about 6 to about 21, more preferably 8 to 18, or a suitable Lewis acid, for example, zinc chloride, bromide or iodide, boron trifluoride, an alkylaluminum oxide or an alkylaluminum chloride, or a suitable Lewis base, for example, a Lewis base of the formula selected from (R.sup.4).sub.3 M' and ##STR10##
M' is P or As;
X.sup.1 is --N-- or --CH, provided, however, when the monomer is a nitrile, X.sup.1 is --CH;
each R.sup.4, independently, is:
each R.sup.5 is --CH.sub.2 CH.sub.2 -- or --CH.sub.2 CH.sub.2 -- containing one or more alkyl or other substituents that are unreactive under polymerizing conditions.
U.S. Pat. Nos. 4,659,782 and 4,659,783 and commonly assigned U.S. patent application Ser. Nos. 627,919filed July 5, 1984 now abandoned; and 771,684, now U.S. Pat. No. 4,695,607; 771,685, now abandoned and 771,686 now abandoned, filed on Sept. 3, 1986, also referred to hereinafter as "the aforesaid patents and patent applications", disclose acrylic star polymers prepared by Group Transfer Polymerization.
Additional details regarding Group Transfer Polymerization can be obtained from the aforesaid patents and patent applications, the disclosures of which are hereby incorporated herein by reference.
It has been found that the presence of a co-catalyst in Group Transfer Polymerization produces "living" polymers with silyl end groups which are extremely sensitive to atmospheric moisture. For this reason, "living" polymers are handled in a dry atmosphere. For some applications, the co-catalyst must be separated from the "living" polymer by means of a difficult purification process. These disadvantages are circumvented in the uncatalyzed polymerization process of the present invention. The process provides a more hydrolytically stable system and allows for simplified purification of "living" polymer product.